In a large skillet add the oil and garlic, then turn the heat to medium. Cook the garlic in the oil until fragrant, about 2 minutes, stirring often (don’t burn it!). Add the spinach and salt and cook for about 6-8 minutes or until the water has cooked out of the spinach, stirring occasionally. Stir in the parsley and cook for 1 more minute.
Transfer to a bowl and stir in the dill (if using) and feta.
You can fry your eggs (if using) in a separate pan while the spinach cooks or just clean out the spinach pan and fry them in there (we’re using the spinach pan to make the grilled cheese, so you’ll have to clean it anyways). I like to break the yolk a little so it’s not super runny, but still a little soft in the sandwich.
Brush olive oil on one side of each slice of bread to lightly but thoroughly coat all over. Flip both over (non-oiled side now facing up). On one slice, add about ½ cup cheese and ¼ of the filling (about ⅓ cup), spreading it into an even layer. Top with the fried egg(s), if using, and then about 1/4 cup more cheese on top. Place the other slice of bread on top (oiled side facing out).
Heat the skillet over medium heat. Once the pan has heated up, carefully add the sandwich, cover with a lid, using it to press the sandwich down, and let cook for about 3-5 minutes, or until cheese is melted and bread is deeply golden. Carefully flip and repeat on the other side.
Slice and serve!